The Blessed Virgin Mary was preserved from the stain of original sin in the first instant of her conception in the womb of her mother. This was a singular privilege and grace of God, granted in view of the merits of Jesus Christ. By her conception is meant not the act or part of her parents in it, nor the formation of her body, nor the conception of Christ later in her own womb; from the moment her soul was created and infused into her body, it was free from original sin and filled with sanctifying grace. Her soul was never stained by original sin, nor by the depraved emotions, passions, and weaknesses consequent on that sin, but created in a state of original sanctity, innocence, and justice. She had at least the graces of the first Eve before the Fall and more. This privilege was befitting the one who was to be mother of the Redeemer.

The doctrine was defined by BlessedPopePius IX, 8 December1854. It is in accord with the texts of Scripture (Genesis 3), “I will put enmities between thee [the serpent] and the woman, and thy seed and her seed”; (Luke 1), “Hail, full of grace.” It is established by tradition, by the writings of the Fathers, by feasts observed in honour of this prerogative, by the general belief of the faithful. The very controversies over it among theologians brought about a clear understanding and acceptance of the doctrine long before it was declared by BlessedPopePius IX. After the declaration, some Protestant writers denounced what they styled Mariolatry (idolatry of Mary). However, there is a constantly-growing devotion among Catholics, and respect among some Protestant groups for the prerogatives of the Mother of Our Redeemer.

Among the many masters who have represented the Immaculate Conception in art are: Carducci, Carreno de Miranda, Falco, Holbein, Montanes, Muller, Murillo, Reni, Ribera, and Signorelli. It is the title she used when appearing at Lourdes.

O God, who by the Immaculate Conception of the Blessed Virgin prepared a worthy dwelling for your Son, grant, we pray, that, as you preserved her from every stain by virtue of the Death of your Son, which you foresaw, so, through her intercession, we, too, may be cleansed and admitted to your presence. Through our Lord Jesus Christ, your Son, who lives and reigns with you in the unity of the Holy Spirit, one God, for ever and ever. – collect prayer, Solemnity of the Immaculate Conception of the Blessed Virgin Mary